From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Murphy Subject: Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver Date: Sat, 12 Jan 2019 11:09:02 -0600 Message-ID: <0140ad64-432e-7723-2415-0b3a8ac4d8dc@ti.com> References: <20181219162626.12297-1-dmurphy@ti.com> <20181219162626.12297-2-dmurphy@ti.com> <2d2d5dcd-9c23-e901-daac-9b79aa5a5e82@ti.com> <6c62956e-7789-58ba-5437-f2e033f2825c@gmail.com> <366cbf6d-94fa-fea9-be58-07ddb09cff3a@ti.com> <1702dfd6-b08f-c1ff-e46d-1366618bedb0@gmail.com> <72112839-11d4-54be-df94-b2322f77cb0f@ti.com> <8b126077-c200-ed34-03b7-6d43a22fb0c9@gmail.com> <92cc81dc-7280-8bf0-9536-9c4d990eaf3b@ti.com> <459a4d7a-980b-5a46-9bd8-7a7afb37e1c3@gmail.com> <76577ad1-8c29-c5f6-e253-a8541a150dc0@ti.com> <3674d644-ccf6-d545-fc41-6bdf8960df44@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <3674d644-ccf6-d545-fc41-6bdf8960df44@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Jacek Anaszewski , robh+dt@kernel.org, pavel@ucw.cz Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org List-Id: linux-leds@vger.kernel.org Jacek On 1/11/19 3:52 PM, Jacek Anaszewski wrote: > Dan, > > On 1/11/19 1:38 PM, Dan Murphy wrote: >> Jacek >> >> Sorry I missed some replies >> >> On 1/10/19 4:03 PM, Jacek Anaszewski wrote: >>> On 1/10/19 9:43 PM, Dan Murphy wrote: >>>> Jacek >>>> >>>> On 1/10/19 1:57 PM, Jacek Anaszewski wrote: >>>>> Dan, >>>>> >>>>> On 1/10/19 8:22 PM, Dan Murphy wrote: >>>>>> Jacek >>>>>> >>>>>> On 1/10/19 12:44 PM, Jacek Anaszewski wrote: >>>>>>> Hi Dan, >>>>>>> >>>>>>> On 1/9/19 10:31 PM, Dan Murphy wrote: >>>>>>>> Jacek >>>>>>>> >>>>>>>> On 1/9/19 3:28 PM, Jacek Anaszewski wrote: >>>>>>>>> On 1/9/19 10:12 PM, Dan Murphy wrote: >>>>>>>>>> On 1/9/19 2:12 PM, Jacek Anaszewski wrote: >>>>>>>>>>> Hi Dan, >>>>>>>>>>> >>>>>>>>>>> On 1/8/19 10:22 PM, Dan Murphy wrote: >>>>>>>>>>>> On 1/8/19 3:16 PM, Jacek Anaszewski wrote: >>>>>>>>>>>>> On 1/8/19 9:53 PM, Dan Murphy wrote: >>>>>>>>>>>>>> Jacek >>>>>>>>>>>>>> >>>>>>>>>>>>>> On 1/8/19 2:33 PM, Jacek Anaszewski wrote: >>>>>>>>>>>>>>> Dan, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On 12/19/18 5:26 PM, Dan Murphy wrote: >>>>>>>>>>>>>>>> Introduce the bindings for the Texas Instruments LP5024 and the LP5018 >>>>>>>>>>>>>>>> RGB LED device driver.  The LP5024/18 can control RGB LEDs individually >>>>>>>>>>>>>>>> or as part of a control bank group.  These devices have the ability >>>>>>>>>>>>>>>> to adjust the mixing control for the RGB LEDs to obtain different colors >>>>>>>>>>>>>>>> independent of the overall brightness of the LED grouping. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Datasheet: >>>>>>>>>>>>>>>> http://www.ti.com/lit/ds/symlink/lp5024.pdf >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Signed-off-by: Dan Murphy >>>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>>>          .../devicetree/bindings/leds/leds-lp5024.txt  | 63 +++++++++++++++++++ >>>>>>>>>>>>>>>>          1 file changed, 63 insertions(+) >>>>>>>>>>>>>>>>          create mode 100644 Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> diff --git a/Documentation/devicetree/bindings/leds/leds-lp5024.txt b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> new file mode 100644 >>>>>>>>>>>>>>>> index 000000000000..9567aa6f7813 >>>>>>>>>>>>>>>> --- /dev/null >>>>>>>>>>>>>>>> +++ b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> @@ -0,0 +1,63 @@ >>>>>>>>>>>>>>>> +* Texas Instruments - LP5024/18 RGB LED driver >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +The LM3692x is an ultra-compact, highly efficient, >>>>>>>>>>>>>>>> +white-LED driver designed for LCD display backlighting. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +The main difference between the LP5024 and L5018 is the number of >>>>>>>>>>>>>>>> +RGB LEDs they support.  The LP5024 supports twenty four strings while the >>>>>>>>>>>>>>>> +LP5018 supports eighteen strings. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Required properties: >>>>>>>>>>>>>>>> +    - compatible: >>>>>>>>>>>>>>>> +        "ti,lp5018" >>>>>>>>>>>>>>>> +        "ti,lp5024" >>>>>>>>>>>>>>>> +    - reg :  I2C slave address >>>>>>>>>>>>>>>> +    - #address-cells : 1 >>>>>>>>>>>>>>>> +    - #size-cells : 0 >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Optional properties: >>>>>>>>>>>>>>>> +    - enable-gpios : gpio pin to enable/disable the device. >>>>>>>>>>>>>>>> +    - vled-supply : LED supply >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Required child properties: >>>>>>>>>>>>>>>> +    - reg : Is the child node iteration. >>>>>>>>>>>>>>>> +    - led-sources : LP5024 - 0 - 7 >>>>>>>>>>>>>>>> +            LP5018 - 0 - 5 >>>>>>>>>>>>>>>> +            Declares the LED string or strings that the child node >>>>>>>>>>>>>>>> +            will control.  If ti,control-bank is set then this >>>>>>>>>>>>>>>> +            property will contain multiple LED IDs. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Optional child properties: >>>>>>>>>>>>>>>> +    - label : see Documentation/devicetree/bindings/leds/common.txt >>>>>>>>>>>>>>>> +    - linux,default-trigger : >>>>>>>>>>>>>>>> +       see Documentation/devicetree/bindings/leds/common.txt >>>>>>>>>>>>>>>> +    - ti,control-bank : Indicates that the LED strings declared in the >>>>>>>>>>>>>>>> +                led-sources property are grouped within a control >>>>>>>>>>>>>>>> +                bank for brightness and mixing control. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Example: >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +led-controller@28 { >>>>>>>>>>>>>>>> +    compatible = "ti,lp5024"; >>>>>>>>>>>>>>>> +    reg = <0x28>; >>>>>>>>>>>>>>>> +    #address-cells = <1>; >>>>>>>>>>>>>>>> +    #size-cells = <0>; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>; >>>>>>>>>>>>>>>> +    vled-supply = <&vbatt>; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    led@0 { >>>>>>>>>>>>>>>> +        reg = <0>; >>>>>>>>>>>>>>>> +        led-sources = <1>; >>>>>>>>>>>>>>>> +    }; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    led@1 { >>>>>>>>>>>>>>>> +        reg = <1>; >>>>>>>>>>>>>>>> +        led-sources = <0 6>; >>>>>>>>>>>>>>>> +        ti,control-bank; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Do you really need ti,control-bank? Doesn't led-sources array size >>>>>>>>>>>>>>> greater than 1 mean that the node describes control bank? >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> That will work too. >>>>>>>>>>>>> >>>>>>>>>>>>>>> Also, does it make sense to have only two LEDs in the bank? >>>>>>>>>>>>>> >>>>>>>>>>>>>> The array can populate all 7 LEDs in a single node.  I only show 2 here as the example. >>>>>>>>>>>>>> See the description above of the led-sources >>>>>>>>>>>>> >>>>>>>>>>>>> OK, I confused RGB LED modules with banks. >>>>>>>>>>>>> >>>>>>>>>>>>> Shouldn't we allow for defining either strings or RGB LED >>>>>>>>>>>>> triplets somehow then? >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Well that is what this should be doing.  If you define a single LED in LED sources then >>>>>>>>>>>> the triplet is controlled via the associated LEDx_brightness register. >>>>>>>>>>> >>>>>>>>>>> led-sources should map to iouts directly. >>>>>>>>>>> So, for RGB LED modules I would expect: >>>>>>>>>>> >>>>>>>>>>> LED0: led-sources = <0 1 2>; >>>>>>>>>>> LED1: led-sources = <3 4 5>; >>>>>>>>>>> LED2: led-sources = <6 7 8>; >>>>>>>>>>> and so on. >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> for banks: >>>>>>>>>>> >>>>>>>>>>> Bank A with iouts 0,3,6,9: led-sources<0 3 6 9>; >>>>>>>>>>> Bank B with iouts 2,4,10:  led-sources<2 4 10>; >>>>>>>>>>> Bank C with iouts 5,8,11,14,17: led-sources<5 8 11 14 17>; >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Ok the led-sources would need to be different then this as I don't define the sources for banks. >>>>>>>>>> >>>>>>>>>> The led-sources for the banks and the individual groups will have different meanings within the same >>>>>>>>>> document.  I was attempting to keep the led-sources mapped to the LEDx_brightness registers as opposed to >>>>>>>>>> the hardware outputs since the RGB LEDs are controlled and grouped by a single brightness register and if banked then >>>>>>>>>> it would be controlled by the bank brightness register. >>>>>>>>>> >>>>>>>>>> Describing these in the DT seems wrought with potential issues as the data sheet defines what outputs map to what bank and LED >>>>>>>>>> registers. >>>>>>>>> >>>>>>>>> Yes, that's why I mentioned the need for validation of led-sources. >>>>>>>>> But they have to be iouts. This property was introduced specifically >>>>>>>>> for such purposes. >>>>>>>>> >>>>>>>> >>>>>>>> Yes Pavel also mentioned that as well. >>>>>>>> >>>>>>>> I will look into validating the sources.  But there will be no mapping of the sources to the output that is done >>>>>>>> in the hardware.  This would just be a data sheet mapping since the outputs are not configurable. >>>>>>> >>>>>>> Hmm, isn't the mapping defined in the hardware via LED_CONFIG0 register? >>>>>>> I have an impression that it defines whether LED belongs to an RGB LED >>>>>>> module or to a bank. Basing on that I created my DT example above. >>>>>>> >>>>>> >>>>>> Yes so if you turn on the bank control for LED0 and LED1 then >>>>>> out 0, 3 are mapped to BANK A >>>>>> out 1, 4 are mapped to BANK B >>>>> >>>>> Just noticed that I made a mistake in my example, it should have been: >>>>> >>>>> Bank B with iouts 1,4,10:  led-sources<1 4 10>; >>>>> >>>>>> out 2, 5 are mapped to BANK C >>>>> >>>>> Correct. >>>>> >>>>>> All done automatically in the hardware and the LED0_BRIGHTNESS and LED1_BRIGHTNESS registers have no affect on the brightness >>>>> >>>>> That's right. >>>>> >>>>>> If we grouped the LEDs into a bank the led-sources would look more like this >>>>>> led-sources = < 0 1 2 3 4 5 >; >>>>> >>>>> Why? This would be a mix of three banks. Like you listed above. >>>>> I'm still interpreting led-sources elements as iout identifiers. >>>>> >>>> >>>> I am as well but as I tried to explain that if you define OUT0 as bank controlled then OUT1 and OUT2 are also bank controlled >>>> within the hardware.  We have no control of that.  If BIT(0) and BIT(1) are set in the LED_CONFIG0 register then OUT0, 1, 2, 3, 4 and 5 are all bank controlled. >>> >>> There is naming conflict I noticed just now - LEDn_BANK_EN bits >>> in LED_CONFIG0 register enable RGB LED modules, and not BANKs (A,B,C). >>> >>>> These OUTPUTs will appear as a single RGB LED grouping. >>> >>> Single? W would rather expect that we get two RGB LED modules, whose >>> brightness will be controlled via LED0_BRIGHTNESS and LED1_BRIGHTNESS >>> registers respectively. >>> >>>>>> ti,control-bank; // But this can be omitted as led-sources is greater then 3 >>>>>> >>>>>> non-banked case would be >>>>>> led-sources = < 0 1 2 >; >>>>> >>>>> Agreed here. It would be LED0 RGB LED module. >>>>>> But the actual OUT numbers don't matter in the bank case unless we do the validation.  There would need to be an algorithim >>>>>> that translates these output to the correct LEDx register and CONFIG0 bits.  Basically if OUT0 is mapped to the bank then OUT1 and OUT2 >>>>>> are inherently mapped to the bank. >>>>> >>>>> To three separate banks, right? >>>>> OUT0 - bank A, OUT1 - bank B, OUT2 - bank C. >>>> >>>> Yes but there is no BANK output pin just like there is no dedicated LEDn output pin.  The banks are grouped internally to the device >>>> so again if OUT0 and OUT3 are defined as banked then 1, 2, 4, and 5 are all mapped to the bank.  1 BANK brightness register and 3 bank >>>> color adjustment registers. >>> >>> Here as above, I would expect two separate banks - LED0 and LED1. >>> Moreover - not 3 color adjustment registers, but six - one per iout: >>> OUT0_COLOR to OUT5_COLOR. >>> >> >> When the LEDs are banked the banked LEDs are controlled by the bank registers not the LEDx registers >> so you should only see 3 color adjustments on the banked LEDs. >> >>>>>> They cannot be separated so the device theoretically treats the RGB group as a single LED.  And >>>>>> when banked it treats the groups of RGBs that are defined as a single LED. >>>>>> >>>>>> This is why it was easier use the LEDx out as the virtual out as we only need to define the group number(s) that are controled by the >>>>>> LED file presented to the user space. >>>>> >>>>> I suspect there is logical clash here due to interpreting >>>>> led-sources elements as iouts in one case and LEDn modules >>>>> in the other case. >>>>> >>>> >>>> Yes.  When the RGBs are banked you have to think of them as a single RGB LED cluster and not as separate RGB LED clusters. >>> >>> We have RGB LED modules (enabled with LEDn_Bank_EN bits) and three >>> banks (A,B,C), which are enabled by default, am I right? >> >> No.  Independent LED modules are enabled by default.  You have to explicitly enable the banks. >> >>> >>> Bank A iouts: 0, 3 ,6, 9, 12, 15 >>> Bank B iouts: 1, 4, 7, 10, 13, 16 >>> Bank C iouts: 2, 5, 8, 11, 14, 17 >>> >>> When RGB LED module is enabled (via LEDn_Bank_EN bit), >>> the BANK_{A.B,C}_COLOR and BANK_BRIGHTNESS registers >>> lose control over related IOUTs in favour of LEDn_BRIGHTNESS and >>> related OUTn_COLOR registers. Is it correct? >> >> No it is the opposite.  When the bit is enabled LED banking is enabled and the BANK brightness and color registers over >> ride the LEDx color and brightness registers. >> >> Default is independent control of the RGB via the LEDx color and brightness registers. >> >>> >>>> As you know the brightness is controlled by the single BANK_BRIGHTNESS register.  So identifying each output in the led-sources is >>>> misleading as the hardware does this all on the chip.  This is why I just mapped each output to the Virtual LEDx module. >>> >>> Ekhm, I messed something here. >>> >>> So for this I would define a single LED class device. >>> Related DT node would not need led-sources at all, >>> but only ti,control-bank. The semantics would be: >>> controls all iouts not taken by RGB LED modules. >>> >> >> Hmm.  I guess I will put that on hold until you read the responses.  I am not sure that would work or >> that would be really clean.  I still believe that mapping led-sources to the LEDx module number is the cleanest >> simplest solution since the driver cannot inter mix different outputs for enablement. > > I've read the doc again more carefully and hopefully I finally have > proper understanding. Let's check it. > > 1. On reset LED_CONFIG0 bits are zeroed, which means >    LEDn module independent control mode. > 2. LEDn modules (i.e. IOUT triplets) are controlled independently, >    with use of LEDn_BRIGHTNESS registers, and each IOUT color can >    be adjusted using OUTn_CONTROL registers. > 3. LEDn_Bank_EN bits, when set to 1, assign given RGB LED module >    to one global bank, controlled via BANK_BRIGHTNESS and BANK_n_COLOR >    registers. > > Having that, I'd see led-sources definitions as follows > (led-sources element is IOUT identifier) > > 1. > > - LED0, LED1, LED2, LED3 modules controlled by separate >   LED class devices > > led-sources = <0 1 2>   // LED0 > led-sources = <3 4 5>   // LED1 > led-sources = <6 7 8>   // LED2 > led-sources = <9 10 11> // LED3 > > 2. > > - LED0 and LED3 modules assigned to the bank, and controlled >   by one LED class device, > - LED1 and LED2 modules controlled by separate LED class devices > > led-sources = <0 1 2 9 10 11> // Bank with LED0 and LED3 > led-sources = <3 4 5>         // LED1 > led-sources = <6 7 8>         // LED2 > > > So now I see your point. It would be indeed easier > to switch to LEDn module identifiers for led-sources > elements. With that the definitions would look like > this: > > > 1. > > - LED0, LED1, LED2, LED3 modules controlled by separate >   LED class devices > > led-sources = <0>   // LED0 > led-sources = <1>   // LED1 > led-sources = <2>   // LED2 > led-sources = <3>   // LED3 > > 2. > > - LED0 and LED3 modules assigned to the bank, and controlled >   by one LED class device, > - LED1 and LED2 modules controlled by separate LED class devices > > led-sources = <0 3> // Bank with LED0 and LED3 > led-sources = <1>   // LED1 > led-sources = <2>   // LED2 > This is exactly how I submitted the code. > > But, I don't think use of led-sources is justified in > this case. I propose to introduce device specific properties: > > ti,led-module and ti,led-bank > > With that we would have: > > ti,led-bank = <0 3>   // Bank with LED0 and LED3 modules > ti,led-module = <1>   // LED1 > ti.led-module = <2>   // LED2 > We are now aligned. I can change the led-sources to the TI specific if there are no further objections. In doing this I can eliminate the ti,control-bank property. > >>> I would also add Table 1 contents (Bank Number and LED Number >>> Assignment) to the DT bindings. >>> >> >> Should I add that to the DT binding or reference the data sheet table since this driver will support 4 different devices >> with varying number of outputs from 18-36. > > My first thought was to show full table, but four different > mappings would add too much noise. So the reference to the data > sheet should suffice. > OK One last question I am going to add the LP5036 and 30 which have the same technology but slightly different register maps. Should I rename the driver to LP5036.c as the 30, 24 and 18 would technically be subsets? Dan -- ------------------ Dan Murphy From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4AA9C43387 for ; Sat, 12 Jan 2019 17:09:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FE132084C for ; Sat, 12 Jan 2019 17:09:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="zHi9AJUH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726460AbfALRJW (ORCPT ); Sat, 12 Jan 2019 12:09:22 -0500 Received: from fllv0016.ext.ti.com ([198.47.19.142]:46582 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725843AbfALRJW (ORCPT ); Sat, 12 Jan 2019 12:09:22 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id x0CH9FsD036113; Sat, 12 Jan 2019 11:09:15 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1547312955; bh=XYRdeJ7WxX5PUHVfWsfUiyBpMAjR8MwxYqBnAgvaKdc=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=zHi9AJUHNBNvpF4BkvBYsLPQP4vtlfvlL9PdY5NkuayXqBnVjyQCKDF5cyAjro2dm AncEW9vYrKYZe3aJY6WBw7APBhgFDl5LhgwRBVA10NgwYfLpvWAUyaazHor4FIG//g v8DoJPyWaALzjJDR7PnhT9PkA4eOamdA7jVmWbss= Received: from DFLE115.ent.ti.com (dfle115.ent.ti.com [10.64.6.36]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x0CH9FGZ044397 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Sat, 12 Jan 2019 11:09:15 -0600 Received: from DFLE106.ent.ti.com (10.64.6.27) by DFLE115.ent.ti.com (10.64.6.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1591.10; Sat, 12 Jan 2019 11:09:15 -0600 Received: from dlep33.itg.ti.com (157.170.170.75) by DFLE106.ent.ti.com (10.64.6.27) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1591.10 via Frontend Transport; Sat, 12 Jan 2019 11:09:15 -0600 Received: from [172.22.68.213] (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep33.itg.ti.com (8.14.3/8.13.8) with ESMTP id x0CH9FJN015439; Sat, 12 Jan 2019 11:09:15 -0600 Subject: Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver To: Jacek Anaszewski , , CC: , , References: <20181219162626.12297-1-dmurphy@ti.com> <20181219162626.12297-2-dmurphy@ti.com> <2d2d5dcd-9c23-e901-daac-9b79aa5a5e82@ti.com> <6c62956e-7789-58ba-5437-f2e033f2825c@gmail.com> <366cbf6d-94fa-fea9-be58-07ddb09cff3a@ti.com> <1702dfd6-b08f-c1ff-e46d-1366618bedb0@gmail.com> <72112839-11d4-54be-df94-b2322f77cb0f@ti.com> <8b126077-c200-ed34-03b7-6d43a22fb0c9@gmail.com> <92cc81dc-7280-8bf0-9536-9c4d990eaf3b@ti.com> <459a4d7a-980b-5a46-9bd8-7a7afb37e1c3@gmail.com> <76577ad1-8c29-c5f6-e253-a8541a150dc0@ti.com> <3674d644-ccf6-d545-fc41-6bdf8960df44@gmail.com> From: Dan Murphy Message-ID: <0140ad64-432e-7723-2415-0b3a8ac4d8dc@ti.com> Date: Sat, 12 Jan 2019 11:09:02 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <3674d644-ccf6-d545-fc41-6bdf8960df44@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jacek On 1/11/19 3:52 PM, Jacek Anaszewski wrote: > Dan, > > On 1/11/19 1:38 PM, Dan Murphy wrote: >> Jacek >> >> Sorry I missed some replies >> >> On 1/10/19 4:03 PM, Jacek Anaszewski wrote: >>> On 1/10/19 9:43 PM, Dan Murphy wrote: >>>> Jacek >>>> >>>> On 1/10/19 1:57 PM, Jacek Anaszewski wrote: >>>>> Dan, >>>>> >>>>> On 1/10/19 8:22 PM, Dan Murphy wrote: >>>>>> Jacek >>>>>> >>>>>> On 1/10/19 12:44 PM, Jacek Anaszewski wrote: >>>>>>> Hi Dan, >>>>>>> >>>>>>> On 1/9/19 10:31 PM, Dan Murphy wrote: >>>>>>>> Jacek >>>>>>>> >>>>>>>> On 1/9/19 3:28 PM, Jacek Anaszewski wrote: >>>>>>>>> On 1/9/19 10:12 PM, Dan Murphy wrote: >>>>>>>>>> On 1/9/19 2:12 PM, Jacek Anaszewski wrote: >>>>>>>>>>> Hi Dan, >>>>>>>>>>> >>>>>>>>>>> On 1/8/19 10:22 PM, Dan Murphy wrote: >>>>>>>>>>>> On 1/8/19 3:16 PM, Jacek Anaszewski wrote: >>>>>>>>>>>>> On 1/8/19 9:53 PM, Dan Murphy wrote: >>>>>>>>>>>>>> Jacek >>>>>>>>>>>>>> >>>>>>>>>>>>>> On 1/8/19 2:33 PM, Jacek Anaszewski wrote: >>>>>>>>>>>>>>> Dan, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On 12/19/18 5:26 PM, Dan Murphy wrote: >>>>>>>>>>>>>>>> Introduce the bindings for the Texas Instruments LP5024 and the LP5018 >>>>>>>>>>>>>>>> RGB LED device driver.  The LP5024/18 can control RGB LEDs individually >>>>>>>>>>>>>>>> or as part of a control bank group.  These devices have the ability >>>>>>>>>>>>>>>> to adjust the mixing control for the RGB LEDs to obtain different colors >>>>>>>>>>>>>>>> independent of the overall brightness of the LED grouping. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Datasheet: >>>>>>>>>>>>>>>> http://www.ti.com/lit/ds/symlink/lp5024.pdf >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Signed-off-by: Dan Murphy >>>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>>>          .../devicetree/bindings/leds/leds-lp5024.txt  | 63 +++++++++++++++++++ >>>>>>>>>>>>>>>>          1 file changed, 63 insertions(+) >>>>>>>>>>>>>>>>          create mode 100644 Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> diff --git a/Documentation/devicetree/bindings/leds/leds-lp5024.txt b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> new file mode 100644 >>>>>>>>>>>>>>>> index 000000000000..9567aa6f7813 >>>>>>>>>>>>>>>> --- /dev/null >>>>>>>>>>>>>>>> +++ b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>>>>>>>>>>>>> @@ -0,0 +1,63 @@ >>>>>>>>>>>>>>>> +* Texas Instruments - LP5024/18 RGB LED driver >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +The LM3692x is an ultra-compact, highly efficient, >>>>>>>>>>>>>>>> +white-LED driver designed for LCD display backlighting. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +The main difference between the LP5024 and L5018 is the number of >>>>>>>>>>>>>>>> +RGB LEDs they support.  The LP5024 supports twenty four strings while the >>>>>>>>>>>>>>>> +LP5018 supports eighteen strings. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Required properties: >>>>>>>>>>>>>>>> +    - compatible: >>>>>>>>>>>>>>>> +        "ti,lp5018" >>>>>>>>>>>>>>>> +        "ti,lp5024" >>>>>>>>>>>>>>>> +    - reg :  I2C slave address >>>>>>>>>>>>>>>> +    - #address-cells : 1 >>>>>>>>>>>>>>>> +    - #size-cells : 0 >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Optional properties: >>>>>>>>>>>>>>>> +    - enable-gpios : gpio pin to enable/disable the device. >>>>>>>>>>>>>>>> +    - vled-supply : LED supply >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Required child properties: >>>>>>>>>>>>>>>> +    - reg : Is the child node iteration. >>>>>>>>>>>>>>>> +    - led-sources : LP5024 - 0 - 7 >>>>>>>>>>>>>>>> +            LP5018 - 0 - 5 >>>>>>>>>>>>>>>> +            Declares the LED string or strings that the child node >>>>>>>>>>>>>>>> +            will control.  If ti,control-bank is set then this >>>>>>>>>>>>>>>> +            property will contain multiple LED IDs. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Optional child properties: >>>>>>>>>>>>>>>> +    - label : see Documentation/devicetree/bindings/leds/common.txt >>>>>>>>>>>>>>>> +    - linux,default-trigger : >>>>>>>>>>>>>>>> +       see Documentation/devicetree/bindings/leds/common.txt >>>>>>>>>>>>>>>> +    - ti,control-bank : Indicates that the LED strings declared in the >>>>>>>>>>>>>>>> +                led-sources property are grouped within a control >>>>>>>>>>>>>>>> +                bank for brightness and mixing control. >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +Example: >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +led-controller@28 { >>>>>>>>>>>>>>>> +    compatible = "ti,lp5024"; >>>>>>>>>>>>>>>> +    reg = <0x28>; >>>>>>>>>>>>>>>> +    #address-cells = <1>; >>>>>>>>>>>>>>>> +    #size-cells = <0>; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>; >>>>>>>>>>>>>>>> +    vled-supply = <&vbatt>; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    led@0 { >>>>>>>>>>>>>>>> +        reg = <0>; >>>>>>>>>>>>>>>> +        led-sources = <1>; >>>>>>>>>>>>>>>> +    }; >>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>> +    led@1 { >>>>>>>>>>>>>>>> +        reg = <1>; >>>>>>>>>>>>>>>> +        led-sources = <0 6>; >>>>>>>>>>>>>>>> +        ti,control-bank; >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Do you really need ti,control-bank? Doesn't led-sources array size >>>>>>>>>>>>>>> greater than 1 mean that the node describes control bank? >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> That will work too. >>>>>>>>>>>>> >>>>>>>>>>>>>>> Also, does it make sense to have only two LEDs in the bank? >>>>>>>>>>>>>> >>>>>>>>>>>>>> The array can populate all 7 LEDs in a single node.  I only show 2 here as the example. >>>>>>>>>>>>>> See the description above of the led-sources >>>>>>>>>>>>> >>>>>>>>>>>>> OK, I confused RGB LED modules with banks. >>>>>>>>>>>>> >>>>>>>>>>>>> Shouldn't we allow for defining either strings or RGB LED >>>>>>>>>>>>> triplets somehow then? >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Well that is what this should be doing.  If you define a single LED in LED sources then >>>>>>>>>>>> the triplet is controlled via the associated LEDx_brightness register. >>>>>>>>>>> >>>>>>>>>>> led-sources should map to iouts directly. >>>>>>>>>>> So, for RGB LED modules I would expect: >>>>>>>>>>> >>>>>>>>>>> LED0: led-sources = <0 1 2>; >>>>>>>>>>> LED1: led-sources = <3 4 5>; >>>>>>>>>>> LED2: led-sources = <6 7 8>; >>>>>>>>>>> and so on. >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> for banks: >>>>>>>>>>> >>>>>>>>>>> Bank A with iouts 0,3,6,9: led-sources<0 3 6 9>; >>>>>>>>>>> Bank B with iouts 2,4,10:  led-sources<2 4 10>; >>>>>>>>>>> Bank C with iouts 5,8,11,14,17: led-sources<5 8 11 14 17>; >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Ok the led-sources would need to be different then this as I don't define the sources for banks. >>>>>>>>>> >>>>>>>>>> The led-sources for the banks and the individual groups will have different meanings within the same >>>>>>>>>> document.  I was attempting to keep the led-sources mapped to the LEDx_brightness registers as opposed to >>>>>>>>>> the hardware outputs since the RGB LEDs are controlled and grouped by a single brightness register and if banked then >>>>>>>>>> it would be controlled by the bank brightness register. >>>>>>>>>> >>>>>>>>>> Describing these in the DT seems wrought with potential issues as the data sheet defines what outputs map to what bank and LED >>>>>>>>>> registers. >>>>>>>>> >>>>>>>>> Yes, that's why I mentioned the need for validation of led-sources. >>>>>>>>> But they have to be iouts. This property was introduced specifically >>>>>>>>> for such purposes. >>>>>>>>> >>>>>>>> >>>>>>>> Yes Pavel also mentioned that as well. >>>>>>>> >>>>>>>> I will look into validating the sources.  But there will be no mapping of the sources to the output that is done >>>>>>>> in the hardware.  This would just be a data sheet mapping since the outputs are not configurable. >>>>>>> >>>>>>> Hmm, isn't the mapping defined in the hardware via LED_CONFIG0 register? >>>>>>> I have an impression that it defines whether LED belongs to an RGB LED >>>>>>> module or to a bank. Basing on that I created my DT example above. >>>>>>> >>>>>> >>>>>> Yes so if you turn on the bank control for LED0 and LED1 then >>>>>> out 0, 3 are mapped to BANK A >>>>>> out 1, 4 are mapped to BANK B >>>>> >>>>> Just noticed that I made a mistake in my example, it should have been: >>>>> >>>>> Bank B with iouts 1,4,10:  led-sources<1 4 10>; >>>>> >>>>>> out 2, 5 are mapped to BANK C >>>>> >>>>> Correct. >>>>> >>>>>> All done automatically in the hardware and the LED0_BRIGHTNESS and LED1_BRIGHTNESS registers have no affect on the brightness >>>>> >>>>> That's right. >>>>> >>>>>> If we grouped the LEDs into a bank the led-sources would look more like this >>>>>> led-sources = < 0 1 2 3 4 5 >; >>>>> >>>>> Why? This would be a mix of three banks. Like you listed above. >>>>> I'm still interpreting led-sources elements as iout identifiers. >>>>> >>>> >>>> I am as well but as I tried to explain that if you define OUT0 as bank controlled then OUT1 and OUT2 are also bank controlled >>>> within the hardware.  We have no control of that.  If BIT(0) and BIT(1) are set in the LED_CONFIG0 register then OUT0, 1, 2, 3, 4 and 5 are all bank controlled. >>> >>> There is naming conflict I noticed just now - LEDn_BANK_EN bits >>> in LED_CONFIG0 register enable RGB LED modules, and not BANKs (A,B,C). >>> >>>> These OUTPUTs will appear as a single RGB LED grouping. >>> >>> Single? W would rather expect that we get two RGB LED modules, whose >>> brightness will be controlled via LED0_BRIGHTNESS and LED1_BRIGHTNESS >>> registers respectively. >>> >>>>>> ti,control-bank; // But this can be omitted as led-sources is greater then 3 >>>>>> >>>>>> non-banked case would be >>>>>> led-sources = < 0 1 2 >; >>>>> >>>>> Agreed here. It would be LED0 RGB LED module. >>>>>> But the actual OUT numbers don't matter in the bank case unless we do the validation.  There would need to be an algorithim >>>>>> that translates these output to the correct LEDx register and CONFIG0 bits.  Basically if OUT0 is mapped to the bank then OUT1 and OUT2 >>>>>> are inherently mapped to the bank. >>>>> >>>>> To three separate banks, right? >>>>> OUT0 - bank A, OUT1 - bank B, OUT2 - bank C. >>>> >>>> Yes but there is no BANK output pin just like there is no dedicated LEDn output pin.  The banks are grouped internally to the device >>>> so again if OUT0 and OUT3 are defined as banked then 1, 2, 4, and 5 are all mapped to the bank.  1 BANK brightness register and 3 bank >>>> color adjustment registers. >>> >>> Here as above, I would expect two separate banks - LED0 and LED1. >>> Moreover - not 3 color adjustment registers, but six - one per iout: >>> OUT0_COLOR to OUT5_COLOR. >>> >> >> When the LEDs are banked the banked LEDs are controlled by the bank registers not the LEDx registers >> so you should only see 3 color adjustments on the banked LEDs. >> >>>>>> They cannot be separated so the device theoretically treats the RGB group as a single LED.  And >>>>>> when banked it treats the groups of RGBs that are defined as a single LED. >>>>>> >>>>>> This is why it was easier use the LEDx out as the virtual out as we only need to define the group number(s) that are controled by the >>>>>> LED file presented to the user space. >>>>> >>>>> I suspect there is logical clash here due to interpreting >>>>> led-sources elements as iouts in one case and LEDn modules >>>>> in the other case. >>>>> >>>> >>>> Yes.  When the RGBs are banked you have to think of them as a single RGB LED cluster and not as separate RGB LED clusters. >>> >>> We have RGB LED modules (enabled with LEDn_Bank_EN bits) and three >>> banks (A,B,C), which are enabled by default, am I right? >> >> No.  Independent LED modules are enabled by default.  You have to explicitly enable the banks. >> >>> >>> Bank A iouts: 0, 3 ,6, 9, 12, 15 >>> Bank B iouts: 1, 4, 7, 10, 13, 16 >>> Bank C iouts: 2, 5, 8, 11, 14, 17 >>> >>> When RGB LED module is enabled (via LEDn_Bank_EN bit), >>> the BANK_{A.B,C}_COLOR and BANK_BRIGHTNESS registers >>> lose control over related IOUTs in favour of LEDn_BRIGHTNESS and >>> related OUTn_COLOR registers. Is it correct? >> >> No it is the opposite.  When the bit is enabled LED banking is enabled and the BANK brightness and color registers over >> ride the LEDx color and brightness registers. >> >> Default is independent control of the RGB via the LEDx color and brightness registers. >> >>> >>>> As you know the brightness is controlled by the single BANK_BRIGHTNESS register.  So identifying each output in the led-sources is >>>> misleading as the hardware does this all on the chip.  This is why I just mapped each output to the Virtual LEDx module. >>> >>> Ekhm, I messed something here. >>> >>> So for this I would define a single LED class device. >>> Related DT node would not need led-sources at all, >>> but only ti,control-bank. The semantics would be: >>> controls all iouts not taken by RGB LED modules. >>> >> >> Hmm.  I guess I will put that on hold until you read the responses.  I am not sure that would work or >> that would be really clean.  I still believe that mapping led-sources to the LEDx module number is the cleanest >> simplest solution since the driver cannot inter mix different outputs for enablement. > > I've read the doc again more carefully and hopefully I finally have > proper understanding. Let's check it. > > 1. On reset LED_CONFIG0 bits are zeroed, which means >    LEDn module independent control mode. > 2. LEDn modules (i.e. IOUT triplets) are controlled independently, >    with use of LEDn_BRIGHTNESS registers, and each IOUT color can >    be adjusted using OUTn_CONTROL registers. > 3. LEDn_Bank_EN bits, when set to 1, assign given RGB LED module >    to one global bank, controlled via BANK_BRIGHTNESS and BANK_n_COLOR >    registers. > > Having that, I'd see led-sources definitions as follows > (led-sources element is IOUT identifier) > > 1. > > - LED0, LED1, LED2, LED3 modules controlled by separate >   LED class devices > > led-sources = <0 1 2>   // LED0 > led-sources = <3 4 5>   // LED1 > led-sources = <6 7 8>   // LED2 > led-sources = <9 10 11> // LED3 > > 2. > > - LED0 and LED3 modules assigned to the bank, and controlled >   by one LED class device, > - LED1 and LED2 modules controlled by separate LED class devices > > led-sources = <0 1 2 9 10 11> // Bank with LED0 and LED3 > led-sources = <3 4 5>         // LED1 > led-sources = <6 7 8>         // LED2 > > > So now I see your point. It would be indeed easier > to switch to LEDn module identifiers for led-sources > elements. With that the definitions would look like > this: > > > 1. > > - LED0, LED1, LED2, LED3 modules controlled by separate >   LED class devices > > led-sources = <0>   // LED0 > led-sources = <1>   // LED1 > led-sources = <2>   // LED2 > led-sources = <3>   // LED3 > > 2. > > - LED0 and LED3 modules assigned to the bank, and controlled >   by one LED class device, > - LED1 and LED2 modules controlled by separate LED class devices > > led-sources = <0 3> // Bank with LED0 and LED3 > led-sources = <1>   // LED1 > led-sources = <2>   // LED2 > This is exactly how I submitted the code. > > But, I don't think use of led-sources is justified in > this case. I propose to introduce device specific properties: > > ti,led-module and ti,led-bank > > With that we would have: > > ti,led-bank = <0 3>   // Bank with LED0 and LED3 modules > ti,led-module = <1>   // LED1 > ti.led-module = <2>   // LED2 > We are now aligned. I can change the led-sources to the TI specific if there are no further objections. In doing this I can eliminate the ti,control-bank property. > >>> I would also add Table 1 contents (Bank Number and LED Number >>> Assignment) to the DT bindings. >>> >> >> Should I add that to the DT binding or reference the data sheet table since this driver will support 4 different devices >> with varying number of outputs from 18-36. > > My first thought was to show full table, but four different > mappings would add too much noise. So the reference to the data > sheet should suffice. > OK One last question I am going to add the LP5036 and 30 which have the same technology but slightly different register maps. Should I rename the driver to LP5036.c as the 30, 24 and 18 would technically be subsets? Dan -- ------------------ Dan Murphy